Abstract This Thesis overviews the methods for calculating the stress intensity factor and employs the stress and displacement methods in the current study. The model used simulates a cracked rectangular plate which is subjected to tensile stress. The Finite element method is used to calculate inplane displacement due to applied loads. As a post processing the stress and stress intensity factor over the plate was calculated. The results show that the singularity exists at the crack tip and the components of stress and approach infinity as the crack tip approach. The comparison of the current study to theoretical and other numerical results shows a good agreement and reliability of the program. The thesis consists of five chapters, the first chapter, presents general over view and historical al review. The second chapter demonstrates the theoretical basis in fracture mechanics. The third chapter involves the numerical solution using F.E.M. The fourth chapter demonstrates a case study and the results and discussion of the obtained results. The fifth chapter concludes the work and gives recommendations.
محمد كامل الشيخ (2009)

This paper is designed to present an experimental study being recently conducted for investigating the effect of some fuel additives on the performance of spark ignition within a benzene engine. Three types of additives were added separately (Gasoline Additive, Gasoline Booster, and Octane Booster) to pure gasoline with a volumetric ratio 1:6, 1:7, and 1:8 respectively. Four separate laboratory experiments being conducted using an internal combustion engine at rotational speed ranges from 600 to 3000 rpm, where the three mixtures and the pure gasoline itself were used. The findings showed that there was a positive effect on the engine performance as the brake power increases by 8%, 13% and 23% at the use of Gasoline Additive, Gasoline Booster, and Octane Booster respectively as compared with using only the pure gasoline. The brake thermal efficiency (ɳth) was also affected positively showing its maximum value of about 8% for Octane Booster, and with a minimum value for using Gasoline Additive at about 4.7%. In addition, this study showed that the value changes in the brake specific fuel consumption for Gasoline Additive, Gasoline Booster, and Octane Booster was at the levels of 1%, 2%, and 5% respectively compared with using only the pure gasoline. Furthermore, the results also showed that the use of Octane Booster gave the highest level of air fuel ratio arabic 18 English 97
ٌRajab HOKOMA, Nabil M. Muhaisen(1-2017)

This paper identifies the most affecting factors that enhance the quality of the decision making process within some Libyan oil and gas companies. Based on the developed questionnaire along with the literature review, the analysis showed that it is a challenge to processing the proper procedure for making decisions. However, most decision makers are found to be focusing on using simple tools for making their decisions, whereas, lacking of an effective communication network during making decisions are considered with a negative impact on making the proper decisions within most surveyed companies. Furthermore, it was found that, the procedures for making decisions within most surveyed companies could be considered as the most crucial for improving the quality of the decision making processes, followed by the used tools and techniques, whereas, communications as a factor influencing the processes of making decisions is found to be at the lowest level throughout the entire decision making processes. arabic 15 English 98
Rajab HOKOMA, Hanan Zawam Aburas(3-2018)